Interesting thread.
In a full-size handgun that fits well, I'm fine with the .40cal, as the extra handgun mass seems to tame things down to where it feels rather "shootable" and recoil isn't much of a factor. Yes, a 9mm is even easier to shoot, but not that much.
In a compact/micro handgun, the .40cal is too much of a handful in my experience. In that role, I'll settle for a 9mm with good ammo. With neither handgun would I expect a solid torso hit or two to put a grown man on the ground with regularity, but they will likely not have much fight in them and the shooter can likely exit the situation. Dispatching deer and hogs with defense pistol loads tells me that handguns kind of suck for providing decisive incapacitations unless you hit CNS.
Another interesting line of thought is the nature of the perpetrator in a civilian vs. LEO shooting. There are a lot of actual shooting videos out there these days and I don't recall many of the "charging bullet-receptacle" scenarios taking place with private citizens. It seems like most of those bad guys hit the road as soon as any bullets were hitting their flesh, regardless of caliber or bullet construction. It was the LEO shootings that saw occurrences of the guys that soaked up so many hits before stopping their attack. Different pools of participants, I suppose.
